Valves for packaging containers

ABSTRACT

A self-closing valve for a packaging container, especially a thin-walled plastics bottle, has an outwardly concave valve head ( 22 ) joined to an outer margin ( 20 ) by a flexible connecting wall ( 24 ). The connecting wall has a frustoconical outer portion ( 56 ) and a cylindrical inner portion ( 57 ) joined together at an elbow ( 58 ). The inner portion ( 50 ) is joined to the valve head at a thin, inturned flange ( 60 ). The outer portion ( 56 ) of the connecting wall is frustoconical and moves between downwardly inclined and upwardly inclined positions as the valve advances to its dispensing position. The outer portion ( 56 ) accordingly imparts a bistable operating characteristic to the valve. The elbow ( 58 ) of the connecting wall ( 24 ) acts as a spring to retract the valve head ( 22 ) quickly after dispensing. The flange ( 60 ) acts as a living hinge, with substantially no flexural stiffness, so that subsequent deformation of the valve head ( 22 ) to allow venting is not resisted.

BACKGROUND OF THE INVENTION

This invention relates to self-closing valves for packaging containers,that is to say, valves which open in response to an elevated pressure ofthe liquid product in a packaging container, and which close againautomatically and in a self-sealing manner when the pressure hassubsequently been reduced to below ambient pressure.

Self-closing valves are well known in the patent literature, andexamples of them are disclosed in published patent specifications EP0545678, EP 0395380, FR 996998, U.S. Pat. No. 2,758,755, U.S. Pat. No.2,175,052 and WO 97/05055 amongst many others. Self-closing valves havebeen proposed for use with a wide variety of liquid foods e.g. ketchups,and household products e.g. washing-up liquids.

The requirements of a self-closing valve to dispense product in acontrolled manner when required and to automatically reseal afterdispensing tend to conflict with one another insofar as theconfiguration of the valve is concerned. Amongst the other requirementswhich may impose further restraints on the valve design are the need forthe valve head to adopt an advanced position for the dispensingoperation, and for the valve to be capable of being readily sealed,against inadvertent operation or dribbling, by a travel head with whichit is engaged up to the point of use. In addition, for cleanliness ofoperation it may be preferred for the valve head at all times to standproud of the closure in which the valve is mounted.

A further desirable characteristic of a self-closing valve is that it iscapable of venting the container headspace in response to small negativepressures which are generated there after dispensing. This is ofparticular concern where the containers are plastics squeeze bottleswhich for economy have a reduced wall thickness, e.g. 0.4 mm, and acorrespondingly reduced ability to resile when they are allowed torelax. Without the ability of the valve to vent, such a container may besubject to unsightly inward panelling and crumpling of its body wall.Satisfactory venting and reclosure of a self-closing valve in responseto negative pressures of 1 kPa or less is therefore desirable.

In attempting to meet the various requirements imposed upon them knownself-closing valves have been made from a substance having advancedphysical properties, in particular of flexibility and resilience. Liquidsilicon such as is marketed by Bayer under the trade name Silopren hasbeen particularly preferred for this purpose, although thermoplasticelastomers have also been contemplated.

These materials are expensive in comparison with the thermoplastic resinmaterials usually used for packaging, and for cost savings it istherefore desirable, as a further objective, to minimise the materialweight of the valve.

SUMMARY OF THE INVENTION

The present invention seeks to provide a self-closing valve whichsatisfies the above requirements to at least a substantial degree. Inaccordance with the invention from one aspect thereof a self-closingvalve for a packaging container comprises (a) a marginal region by whichthe valve may be peripherally secured to a housing so as to close anopening in the same, (b) a valve head having an openable dispensingaperture and movable axially in relation to the marginal region betweenan advanced, dispensing position in which the aperture is open andproduct may be dispensed under pressure and a retracted, inoperativeposition in which the aperture is closed and the valve head forms a sealand (c) a connecting wall which is imperforate and flexible andcomprises first and second portions serially arranged between themarginal region and the valve head and joined together at a V-formelbow, the first portion extending inwardly from the marginal region tothe elbow, the second portion extending generally axially from the elbowto peripheral attachment with the valve head, and the connecting wallbeing of increased wall thickness at the elbow whereby during operationof the valve the elbow may keep its identity and act resiliently as aspring for returning the valve head to its retracted position.

The first portion of the connecting wall may be substantiallyfrustoconical when the valve head is in each of its retracted andadvanced positions, extending inwardly and downwardly away from thevalve head in its retracted position, and extending inwardly andupwardly towards the valve head in its advanced position. In this waythe connecting wall may be arranged to give a bistable operatingcharacteristic to the valve at a positive pressure of typically 3 to 5kPa.

As an alternative to providing bistable operation for the valve, thefirst portion of the connecting wall may be arranged to move from asubstantially frustoconical, inwardly and downwardly extendingunstressed position to a substantially plane, metastable position as thevalve head moves between its retracted and advanced positions. In thisway it may be arranged to provide substantial assistance to the elbow toreturn the valve head resiliently to its retracted position. DE 196 13130 discloses a self-closing valve in accordance with theprecharacterising part of claim 1. The valve has a thickened portion ofits connecting wall designed for variously acting as a passive abutmentwith the closure structure and with a further part of the connectingwall. In particular, the connecting wall of the valve of DE 196 13 130has no V-form elbow capable of acting as a spring to return the valvehead to its retracted position.

In accordance with a second aspect thereof a self-closing valve for apackaging container comprises (a) a marginal region by which the valvemay be peripherally secured to a housing so as to close an opening inthe same, (b) a valve head having a dispensing aperture formed in acentral part thereof and openable to allow product to be dispensed underpressure, the valve head being self-closable to form a seal when theproduct pressure subsequently abates and (c). a connecting wall which isimperforate and flexible and connects the marginal region with the valvehead, characterised in that the connecting wall has a substantiallycylindrical first part and an inturned, substantially radially extendingsecond part by which the first part is attached to the valve headperiphery, the thickness of the valve head reducing from the valve headperiphery inwardly towards the dispensing aperture, and the second partof the connecting wall having a thickness which is at most one third ofthe thickness of the valve head periphery and such that during operationof the valve the second part may act as a living hinge, withsubstantially no flexural stiffness.

Preferably, the at-rest position of the valve in use is the same as theposition in which it is manufactured.

In conjunction with the substantial lack of flexural stiffness of thesecond part of the connecting wall, this feature assists venting.

In order that the invention may be more fully understood, self-closingvalves embodying the invention will now be described, by way of example,with reference to the accompanying drawings. Of the drawings:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 diagrammatically shows a first valve and the adjacent part of thehousing in which it is mounted, the valve being shown in centralcross-section and in its retracted or “at rest” position;

FIGS. 2A through 2G are views identical to FIG. 1 but to a smallerscale, showing the first valve at several stages during its operation todispense product and subsequently return to its retracted position;

FIG. 3 shows the first valve in perspective view and as seen on adiametral section to a larger scale than FIGS. 1 and 2;

FIGS. 4A through 4C show a second valve in accordance with theinvention, in views similar to some of those of FIG. 2; and

FIGS. 5A through 5C correspondingly show a third valve in accordancewith the invention, in views similar to some of those of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring firstly to FIGS. 1 to 3 of the drawings, a self-closing valve10 is mounted in a housing 12, only part of which is shown. The housinghas an opening 13 in which the valve is located. The housing forms partof a plastics closure which is itself mounted on a plastics container ofa liquid food or other product. The closure may be a snap cap but moreusually it will be a screw cap.

The container (not shown) is squeezable to expel product through thevalve, and it is resilient so as after a dispensing operation togenerate a negative pressure within the container headspace 14 and socause the valve 10 to return to the as-moulded, retracted conditionshown in FIG. 1. The behaviour of the valve during its dispensing andretracting movements will be described later in detail.

The valve 10 is a unitary moulding of a suitable flexible and resilientmaterial, Liquid Silicon Rubber sold by Bayer under the trade nameSilopren being preferred. It has three parts, namely a thickenedmounting ring 20 which forms a continuous marginal region around thevalve, a valve head 22 capable of movement axially of and within themounting ring between the retracted position shown in FIG. 1 and theadvanced position at which dispensing takes place—See FIGS. 2D, 2E—andan imperforate connecting wall 24 which connects the mounting cup withthe valve head.

The mounting ring 20 is generally triangular in cross-section, having acylindrical outer face 30, and inclined upper and lower faces 26 and 28which converge inwardly of the valve towards the attachment of theconnecting wall 24.

For engaging and holding the valve 10 the housing 12 has upper and lowerparts 32 and 34 which are snap-engaged together by resilient engagementof complementary snap formations 36 and 38. Opposed inclined surfaces ofthe parts engage the faces 26, 28 of the mounting ring to hold itsecurely in position in a sealing manner.

In the embodiment shown, the lower part 34 of the housing forms anintegral part of a screw closure onto which the upper part 32 issnap-engaged. By suitable modification, however, the upper part may beincorporated into the closure, and the lower part be provided as aseparate component which is fitted to it.

The valve head 22 is concave to the exterior of the closure and is ofprogressively reducing thickness in the direction of its centre line XXfrom the cylindrical face 40 which forms its outer periphery. Itsexterior face 42 is arcuate, and its interior face 48 is arcuate exceptat a central flat 51. The outer cylindrical face 40 and the exteriorface 42 converge to a sharply defined circular free edge 50 which formsthe topmost point of the valve head as shown.

From FIG. 3 it will be understood that the valve head 22 is formed withtwo identical straight cuts 52A, 52B, which intersect at their midpointson the centreline XX. The cuts are orthogonal to one another, and eachcut extends through the thickness of the valve head. In combination thecuts therefore form four individually movable triangular tongues 53attached to the valve head along the sides of a square and having theirapices coincident on the centreline.

One of the tongues is shown in full in FIG. 3. Also visible in FIG. 3 isa ring formed of eight regularly spaced bosses 54 which project inwardlyfrom the connecting wall 24 adjacent its bottom edge 55. The bossesprevent nesting of the valves together prior to their automatic assemblyinto housings 12. For clarity, they are omitted from the other drawings.

The connecting wall 24 has outer and inner parts 56, 57 connected at anelbow 58. When the valve is in its as-moulded, retracted position, i.e.as shown in FIG. l, the outer part is frustoconical, so as to extendinwardly and downwardly between the mounting ring 20 and the elbow. Theinner part 57 of the connecting wall is cylindrical, extending axiallybetween the elbow and a radially extending, short and thin, inturnedflange 60 at which it is connected to the cylindrical outside face 40 ofthe valve head 22. The height of the side face 40 of the valve head is1.87 mm, and the thickness of the flange is 0.3 mm; thus, the valve headis more than six times the thickness of the flange at the junctionbetween them.

The flange 60 is attached to the side face 40 of the valve head at aspacing of 0.46 mm below the top free edge 50 of the valve head. Thepart of the valve head lying above the flange and including the freeedge 50 accordingly defines an upwardly tapering and relativelycompliant lip 59 which is capable of promoting drip-free product flowand of forming a product-tight seal against a flat surface of a travelcap (not shown) if required. For this purpose, and as can be seen fromthe drawings, the lip projects above the surrounding upper surface ofthe housing at all times during operation of the valve.

The outer part 56 of the connecting wall 24 is inclined at an angle of45° to the centreline XX of the valve, and therefore to the inner part57. The substantially V-shaped notch which is formed between the twoparts is denoted by the reference numeral 72.

The material thickness of the outer wall part 56 is uniform, at 0.31 mm.With the exception of the connecting flange 60 the inner wall part 57likewise has a uniform thickness, its thickness being 0.40 mm, that is,somewhat greater than that of the outer wall part and of the flange 60.

The outer wall part 56 has upper and lower surfaces 62, 64 respectively,the inner wall part 57 having outer and inner surfaces 66, 68. Thebottom edge 55 of the connecting wall 24 is a plane annular face formedwhere the inner wall part intersects the lower surface 64 of the outerwall part at the base of the elbow 58. The material thickness at theelbow is therefore substantial, being 0.94 mm as measured from thebottom inner corner of the elbow to the acute-angled notch 72 at whichthe mutually facing surfaces 62, 66 intersect one another. The elbowaccordingly has a substantial rigidity against forces which tend to openit by separating the surfaces 62, 66 in its location; in particular itis capable of acting as a spring, as will later be described.

FIG. 3 illustrates a modification of the valve, in which the ring ofspaced bosses 54 previously described is replaced by an inwardlyprojecting continuous bead 54A of rectangular cross-sectioncorresponding in location and cross-sectional dimensions (radial depthand axial height) to those of the ring of bosses. In addition topreventing nesting of adjacent valves prior to their assembly inhousings 12, the bead increases the stiffness of the connecting wall 24at the elbow 58, and assists in the valve moulding operation by enablingthe valve to be held securely on the mould core until it can bestripped, under full control, from the mould core.

Reference is now made to the various parts of FIG. 2 which show thevalve in successive stages of its operation to dispense product andsubsequently to retract with venting of air into the container interior.

FIG. 2A is a reproduction of FIG. 1 and shows the as-moulded, retractedposition of the valve which occurs when little or no pressuredifferential exists across the wall of the container.

When it is required to dispense product the container is squeezed by theuser to generate a substantial overpressure of, typically, 3 to 5 kPawithin the container. In response to this pressure the valve head rises,accompanied by inversion of the outer part 56 of the connecting wall 24from its original “down” (i.e. downwardly and inwardly extending)position to the “up” (i.e. upwardly and inwardly extending) positionwhich exists during product dispensing (See FIG. 2E).

In each of its “down” and “up” limiting positions the outer wall part 56is generally frustoconical. In its movement between these positions itpasses through the metastable intermediate condition shown in FIG. 2B,in which it has maximum internal stress and stored energy. It thereforeimparts a desired bistable operating characteristic at a positivepressure to the valve. In FIG. 2C the outer wall part is approaching its“up” position; and in FIGS. 2D and 2E it has reached its “up” position.

The movement of the outer wall part 56 is largely passive, and caused bythe generally axial forces transmitted to it by the inner wall part 57.A minor part of the motive force, however, will be generated by theproduct pressure on the outer wall part itself.

As will be understood from a comparison of FIGS. 2A to 2E, the movementof the outer wall part 56 is accompanied by hinging movement of theouter wall part on the mounting ring 20 at the attachment between them,together with opening of the elbow 58 to an obtuse angle ofapproximately 120° at its notch 72. Some distortion of the wall parts56, 57 individually will also occur, both in response to the productpressure and in order to accommodate the opening of the elbow and itstranslational inward movements which accompany the inversion of theouter wall part. However, at all times the outer wall part remainssubstantially frustoconical or plane, and the inner wall part remainssubstantially cylindrical.

A comparison of FIGS. 2A to 2E clearly shows the behaviour of the valvehead 22 during a movement from its retracted position in FIG. 2A to itsadvanced dispensing portion (FIG. 2E). It will be seen that in responseto product pressure the head becomes progressively less concave andflattened as the tongues 53 flex and hinge in an upward direction abouttheir attachment to the remainder of the valve head. At about the timethat the advanced position of the head is reached (FIG. 2D) andtypically at a pressure of 5 to 8 kPa, the tongues pass a dead-centreposition at which they are approximately coplanar; thereafter, withfurther flexing and hinging movement in the upward direction theyseparate from one another to leave an aperture generally in the form ofa cross and through which product may be dispensed as indicated by thearrow 70.

After dispensing has occurred the user relaxes his grip on theassociated container, and the pressure in the container headspace 14falls and eventually becomes negative as the container resiles. Inresponse to the falling pressure the valve head 22 is moved quickly backto its retracted position by the resilience of the elbow 58 togetherwith a minor contribution from relaxation of longitudinal stress in thecomponent parts of the connecting wall 24; at the same time the headreturns to its original position by virtue of the resilience provided byits own relatively thickwalled construction. FIG. 2F shows thissituation; the valve has the same general appearance as in FIGS. 1, 2Aand 3, but at this time the pressure in the container headspace isbecoming negative and venting is required to allow the container fullyto resile. This is accomplished by continued downward flexing andhinging movement of the tongues 53 in relation to the valve head 22 as awhole, until they can separate sufficiently to allow air to relieve thepressure differential. In this way residual panelling or crumpling ofthe container can be avoided. In FIG. 2G the venting aperture is shownand indicated by the reference 71. After venting the tongues return totheir position shown in FIG. 2F.

The spring action of the elbow 58 assists the movement of the valve headback to its retracted position after dispensing. This is of particularvalue where the associated container is of thin-walled construction(e.g. less than 0.4 mm or less in thickness) and has a correspondinglimited resilience. The elbow ensures a quick returning action of thevalve and provides the valve with a positive “feel” for the user.

As previously mentioned, the flange 60 by which the connecting wall 24is attached to the valve head 22 is thin, having a wall thickness ofonly 0.3 mm. It will be seen from FIGS. 2A to 2E that as the valve movestowards its dispensing condition (FIG. 2E) the outer face 40 of thevalve head and the part of the connecting wall 24 which lies oppositeare required to separate from one another. Because it has little or noflexural stiffness, the flange presents little or no resistance to thisseparating movement. It acts essentially as a living hinge attachment bywhich translational movements of the valve head and the connecting wallmay be transmitted from one to the other. Moreover, because theretracted position of the valve (shown in FIGS. 2A, 2F) is also theas-moulded position in which it is manufactured, the flange 60 issubstantially without stress when the valve is in that position. Becauseof this lack of stress any flexural stiffness which the flange doespossess will not create torsional forces in the valve head in the senseto resist the distortion of the valve head which is required for it tovent, i.e. as depicted in FIG. 2G. Applicants believe that the thicknessof the flange 60 should be at most one third of the thickness of thevalve head periphery.

In the second embodiment, shown in FIG. 4, the valve 10 is exactly ashas been described in relation to the first embodiment and accordinglyit is not described again. The housing 12, however, is modified byradially inward extension of its upper part 32 to provide an annularnose 74. As the connecting wall 24 moves generally upwardly andoutwardly during its movement for product dispensing, its elbow 58 comesinto nesting engagement with this nose of the housing so as to definethe vertical position which the head adopts for dispensing—See FIG. 4C.In contrast, in the first embodiment the connecting wall does not engagethe housing, and the position of the head for dispensing is determinedentirely by the dynamic balance of the forces in the connecting wall andthe valve head.

Of the various parts of FIG. 4, FIGS. 4A, 4B and 4C show stages ofoperation of the valve corresponding to those represented in FIGS. 2A,2B and 2C respectively. The stages of operation corresponding to thoseof FIGS. 2D to 2E likewise correspond, but they are not shown.

FIG. 5 shows a third embodiment of the invention to be similar to thatof FIG. 4 in that the dispensing position of the valve head 22 islikewise determined by engagement of the connecting wall 24 with theupper part 32 of the housing 12. In this embodiment the engagement ismade between the upper surface 62 of the outer wall part 56 and thecomplementary undersurface 75 of an annular nose 76 formed on the upperpart 32 of the housing.

In FIG. 5 its engagement with the housing 12 restricts the upwardmovement of the outer part 56 of the connecting wall 24 to thesubstantially horizontal and plane position shown in FIGS. 5B and 5C.This will be seen to correspond approximately to the unstable positionrepresented in FIGS. 2B and 4B for the earlier embodiments. By revertingto its unstressed, low energy condition the outer wall part 56 thereforeassists the elbow 58 to return the valve resiliently to its retractedposition after dispensing.

From FIG. 5A in particular it will be seen that the outer and innerparts 56, 57 of the connecting wall 24 are made longer than in theearlier embodiments, being correspondingly inclined to one another by asmaller acute angle of approximately 30° at the elbow 58. This increasedlength of the parts of the connecting wall compensates in part for therestricted movement which is available, caused by the engagement by thenose 76 as described.

In the various parts of FIG. 5, FIGS. 5A, 5B and 5C can be considered toshow the stages of operation which correspond to those of FIGS. 2A, 2Band 2E of the first embodiment.

In the embodiments of the invention described above the valve heads 22and their attachments to the connecting wall 24 by the connecting valve60 are identical, and because of the isolating function of theconnecting flange the valve heads operate in a substantially identicalmanner.

In all the embodiments described above, the periphery of the valve head22 stands proud of the adjacent surrounding part of the housing 12 atall times, in particular in the “at rest” position of the valve.Together with the shape of the compliant portion 59 which forms thevalve periphery, this proudness helps promote clean operation of thevalve during dispensing, with little or no dripping when the containerhas been inverted again after dispensing in a valve-down position. Inthis respect it should be noted that the invention may have applicationto containers which are normally in a valve-down position, such forexample, as liquid soap dispensers intended to be mounted in an invertedposition on a wall, as well as to containers which require to beinverted for use.

Although a preferred embodiment of the invention has been specificallyillustrated and described herein, it is to be understood that minorvariations may be made in the apparatus without departing from thespirit and scope of the invention, as defined the appended claims.

What is claimed is:
 1. A self-closing valve for a packaging container,which comprises (a) a marginal region (20) by which the valve (10) isperipherally secured to a housing (12) so as to close an opening (13) inthe same, (b) a valve head (22) having an openable dispensing aperture(70) and movable axially in relation to the marginal region between anadvanced, dispensing position in which the aperture is open and productis dispensed under pressure and a retracted, inoperative position inwhich the aperture is closed and the valve head forms a seal, and (c) aconnecting wall (24) which is imperforate and flexible, characterized inthat the connecting wall (24) comprises first and second portions (56,57) serially arranged between the marginal region (20) and the valvehead (22) and joined together at a V-form elbow (58), the first portion(56) extending inwardly from the marginal region to the elbow, thesecond portion (57) extending generally axially from the elbow toperipheral attachment with the valve head, and the connecting wall beingof increased wall thickness at the elbow whereby during operation of thevalve the elbow may keep its identity and act resiliently as a springfor returning the valve head to its retracted position.
 2. A valve inaccordance with claim 1, characterized in that the first portion (56) ofthe connecting wall (24) is substantially frustoconical when the valvehead (22) is in each of its retracted and advanced positions, said firstportion (56) extending inwardly and downwardly away from the valve headin its retracted position, and said first portion (56) extendinginwardly and upwardly towards the valve head in its advanced position,the valve operating bistably between its retracted and advancedpositions at a positive pressure.
 3. A valve in accordance with claim 1,characterized in that the first portion (56) of the connecting wall (24)is arranged to move from a substantially frustoconical, inwardly anddownwardly extending unstressed position to a substantially plane,metastable position as the valve head (22) moves between its retractedand advanced positions.
 4. A valve in accordance with claim 1,characterized in that the connecting wall (24) has an inturned,substantially radially extending flange (60) by which it is attached toa valve head periphery (40), the thickness of the valve head (22)reducing from the valve head periphery inwardly towards the dispensingaperture (70), and the flange of the connecting wall having a thicknesswhich is at most one third of the thickness of the valve head peripheryand such that during operation of the valve the valve acts as a livinghinge, with substantially no flexural stiffness.
 5. A valve according toclaim 1, characterized in that an at-rest position of the valve (10) inuse is the same as the position in which it is manufactured.
 6. A valveaccording to claim 1, characterized by means (54, 54A) for inwardlyprojecting from the connecting wall (24) adjacent the elbow (58).
 7. Avalve in accordance with claim 6, characterized in that the means forinwardly projecting comprises a ring of spaced bosses (54).
 8. A valvein accordance with claim 6, characterized in that the means for inwardlyprojecting comprises a continuous bead (54A).
 9. A valve in accordancewith claim 1, in combination with the housing (12) by which the valve(10) is mounted in sealing relation at its marginal region (20).
 10. Acombination in accordance with claim 9, characterized in that at alltimes during movement of the valve (10) between its retracted andadvanced positions, its connecting wall (24) and head (22) are spacedfrom the housing (12).
 11. A combination in accordance with claim 9characterized in that as the valve (10) moves from its retracted to itsadvanced positions the elbow (58) of the connecting wall (24) comes intorestraining engagement with the housing (12).
 12. A combination inaccordance with claim 9 characterized in that as the valve (10) movesfrom its retracted to its advanced positions the first portion (56) ofthe connecting wall (24) comes into restraining engagement with thehousing (12).
 13. A combination in accordance with claim 9,characterized in that around an upper periphery the valve head (22) hasa compliant and tapering lip (59) which stands proud of the housing (12)at all times during operation of the valve.